The field of the invention relates generally to turbine engines, and more particularly, to combustors and fuel nozzle assemblies within turbine engines.
At least some known turbine engines include a forward fan, a core engine, and a power turbine. The core engine includes at least one compressor that provides pressurized air to a combustor where the air is mixed with fuel and ignited for use in generating hot combustion gases. Many such known turbine engines typically include a plurality of fuel nozzles for supplying fuel to the combustor in the core engine. The fuel is introduced at the front end of a burner in a highly atomized spray from at least one of the fuel nozzles. Compressed air flows around the fuel nozzle and mixes with the fuel to form a fuel-air mixture, which is ignited by the burner. The fuel nozzles have swirler assemblies that swirl the air passing through them to promote mixing of air with fuel prior to combustion. The swirler assemblies used in the combustors may be complex structures having axial, radial, or conical swirlers or a combination of them. Generated combustion gases flow downstream to one or more power turbines that extract energy from the gas to power the compressor and provide useful work, such as powering an aircraft.
In at least some known combustors, fuel and air are injected into an oxidizer stream from respective pluralities of circumferentially-spaced outlets. The independent streams of fuel and air interact to form a mixture, which produces a lean combustion flame that reduces NOx emissions. However, in some known systems, the fuel nozzles are configured such that fuel injection through the fuel nozzles sometimes results in fuel directed towards the liners of the combustor where combustion occurs. Such close proximity of combustion to the liners increases their thermal loading, thereby decreasing a margin to thermal parameters of the liners and potentially decreasing their service life. In general, in some such known fuel nozzles, the fuel nozzles include a plurality of circumferentially positioned fuel feed apertures that are substantially similar in size. A clockwise swirl within the fuel nozzle entrains fuel injected through the apertures at substantially similar fuel flow rates and some of the fuel injected from certain apertures is directed toward the liners.